Case 38 Answer: Xanthogranulomas of the choroid plexus (bilateal)

Completely incidental and benign.

Nice Radiopaedia write-up: http://radiopaedia.org/articles/choroid-plexus-xanthogranuloma

Old AJR article: http://www.ajronline.org/doi/pdf/10.2214/ajr.143.2.401